ADC081S021CISD - 8-Bit 50-200 ksps SAR ADC | Texas Instruments
MPN: ADC081S021CISD ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.65 | $1.65 |
| 10 | $1.45 | $14.50 |
| 100 | $1.18 | $118.00 |
| 500 | $0.95 | $475.00 |
| 1,000 | $0.81 | $810.00 |
| 3,000 | $0.65 | $1,950.00 |
ADC081S021CISD Overview
An ADC (analog-to-digital converter) is a semiconductor device that converts a continuous analog voltage or current into a discrete digital code. SAR ADCs in particular perform conversion by binary-search approximation: a comparator and a switched capacitor DAC iteratively narrow the unknown input voltage against internal reference levels over N clock cycles for an N-bit result. SAR ADCs occupy the middle ground between flash converters (fastest, lowest resolution) and sigma-delta ADCs (slowest, highest resolution), and dominate applications requiring single-shot or burst-mode acquisition with deterministic latency. ADC081S021 belongs to the data-converter -> ADC -> SAR ADC -> 8-bit SAR product hierarchy in the TI portfolio.
Key specifications include 8-bit resolution, 50-200 ksps sample rate, single 2.7-5.25 V supply, true-differential analog input (VIN+ / VIN-), SPI-compatible serial output, and an INL/DNL of 0.2 LSB / 0.1 LSB (typical). The supply is also used as the reference, simplifying external BOM. Typical power consumption is 1.3 mW at 3.6 V / 200 ksps and drops to <1 µW in shutdown. Operating temperature is -40 °C to +85 °C (industrial grade).
The ADC081S021 architecture includes an input track-and-hold, a charge-redistribution DAC, a high-speed comparator, and a SAR control logic block. The SCLK, /CS, and DOUT pins implement a standard 3-wire SPI interface, allowing direct connection to most microcontrollers and DSPs without glue logic. The compact 6-WSON package makes the part especially attractive for space-constrained designs.
Typical applications include portable/battery-powered instrumentation, consumer audio front ends, system monitoring and housekeeping ADCs, isolated sensor front ends, and industrial process-control monitoring. The wide 2.7 V to 5.25 V supply range allows direct connection to 3.3 V and 5 V rails.
When designing with this ADC, bypass VA with a 0.1 µF ceramic capacitor placed as close as possible to the supply pin, and keep analog input traces short to minimize coupling. Because the supply doubles as the reference, any noise on VA directly converts to noise in the conversion result, so a clean, low-ripple rail is critical.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, giving procurement and design engineers a one-stop reference for sourcing and using the ADC081S021CISD.
Drop-in alternatives for ADC081S021CISD — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ADC081S021CISD (same form factor and footprint) — differing in Package, Digital Interface, Resolution, Architecture, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ADC081S021CISD/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
ADC101S021CISD
✅ Drop-In📋 Reference alternative (not in catalog)
ADC121S021CISD
✅ Drop-In✓ In Stock
$1.79 / Unit
View Datasheet →ADC081S021CIMFD
✅ Drop-In📋 Reference alternative (not in catalog)
ADC081S021CIMF/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
ADC081S021CISD Maximum Ratings & Electrical Characteristics
| Resolution | 8 bit |
| Sample Rate | 50 ksps to 200 ksps |
| Architecture | SAR (Successive Approximation Register) |
| Number of Channels | 1 |
| Supply Voltage (VA) | 2.7 V to 5.25 V |
| Analog Input Type | Single-ended (true-differential VIN+ / VIN-) |
| Reference | Supply-referenced (VA) |
| Integral Nonlinearity (INL) | ±0.2 LSB (typ) / ±0.5 LSB (max) |
| Differential Nonlinearity (DNL) | ±0.1 LSB (typ) / ±0.5 LSB (max) |
| Power Consumption (3.6 V, 200 ksps) | 1.3 mW (typ) |
| Shutdown Current | <1 µA |
| Digital Interface | SPI/QSPI/MICROWIRE-compatible (3-wire) |
| Package | 6-WSON (2.2 mm x 2.5 mm) with exposed pad |
| Operating Temperature | -40 °C to +85 °C (industrial) |
| MSL Level | 1 |
| RoHS Status | Compliant |
| Lead-Free | Yes |
ADC081S021CISD Pin Configuration
| Pin 1 | VA — Analog supply voltage (2.7 V to 5.25 V); also serves as reference |
| Pin 2 | GND — Ground |
| Pin 3 | VIN+ — Non-inverting analog input |
| Pin 4 | VIN- — Inverting analog input (true-differential) |
| Pin 5 | DOUT — Serial data output (SPI MOSI from ADC) |
| Pin 6 | SCLK — Serial clock input |
Typical Applications
ADC081S021CISD is suitable for 6 applications: Battery-Powered Portable Instrumentation, System Health / Housekeeping Monitoring, Consumer Audio Front-End Level Sensing, Industrial Process Control and 4-20 mA Loop Monitoring, Isolated Sensor Front Ends (SPI over Digital Isolator), LED Driver Feedback and Lighting Control.
Battery-Powered Portable Instrumentation
The ADC081S021CISD fits portable handheld instruments because its 1.3 mW typical power at 200 ksps and sub-1 µA shutdown current extend battery life. Its 6-WSON (2.2x2.5 mm) footprint leaves room for small Li-ion cells and a small display. The single 2.7-5.25 V supply allows direct connection to a single Li-ion / 2xAA stack without an extra regulator, while the SPI-compatible 3-wire interface reduces GPIO use on resource-constrained MCUs. Designers typically run the part at the low end of its sample-rate range (a few ksps) for sensor monitoring, dropping shutdown current to nanowatts between bursts.
Recommended
System Health / Housekeeping Monitoring
Inside rack-mounted servers, switches, and base stations, the ADC081S021CISD serves as a low-cost housekeeping ADC that digitizes supply rails, temperatures via thermistors, and fan tach signals. Its 8-bit resolution is sufficient for go/no-go threshold alarms, and the SAR architecture delivers a deterministic single-cycle latency - critical when the host must react to a fault within a known number of clocks. The supply-as-reference topology eliminates one external reference part, reducing BOM cost on high-density line cards where every square millimeter and every component counts.
Recommended
Consumer Audio Front-End Level Sensing
In low-cost audio docks and TV sets, the ADC081S021CISD can monitor a peak-detected line-level signal for compressor/limiter control or VU-metering. Its 50-200 ksps sample rate comfortably tracks envelope changes in voice-band audio, and its 2.7-5.25 V supply accepts both 3.3 V and 5 V analog rails common in consumer audio. Because the converter uses VA as the reference, design teams must ensure the analog supply is adequately filtered - any ripple on VA appears directly on the conversion result. The 6-WSON package mounts on the underside of a crowded main board next to the audio codec.
Recommended
Industrial Process Control and 4-20 mA Loop Monitoring
In industrial PLCs and remote telemetry units, the ADC081S021CISD digitizes 4-20 mA current-loop receivers and 0-10 V process signals after a front-end op-amp buffer. Its industrial -40 °C to +85 °C operating range suits factory-floor enclosures, and the small 6-WSON package fits on tightly packed analog-input modules. The SAR architecture gives single-cycle conversion latency, simplifying closed-loop control math. The wide supply range accepts the 24 V industrial bus after a downstream DC-DC converter, while the SPI output streams data to a host MCU or FPGA for scaling and alarm decisions.
Recommended
Isolated Sensor Front Ends (SPI over Digital Isolator)
The ADC081S021CISD pairs naturally with a digital isolator (e.g., TI ISO7241 or ADuM1411) to form a compact isolated analog-input module for medical or industrial sensors. Mounting the ADC on the high-voltage or patient-side of the isolation barrier keeps the analog signal path short and avoids running analog signals across the isolator. The 3-wire SPI interface translates cleanly through standard digital isolators. Designers use the wide 2.7-5.25 V supply to power the ADC directly from an isolated DC-DC converter winding, simplifying the isolated-side BOM to the ADC plus bypass caps.
Recommended
LED Driver Feedback and Lighting Control
In LED drivers and tunable-white lighting controllers, the ADC081S021CISD monitors photodiode current, color sensor outputs, or driver current-sense amplifiers to close a brightness/color loop. Its 8-bit resolution is adequate for backlight dimming or simple color-temperature adjustment, and the SPI interface lets the lighting MCU read multiple ADC081S021 devices on a shared bus with separate /CS lines. The 6-WSON package mounts on the small PCB inside an LED bulb or downlight fixture, and the 2.7-5.25 V supply accepts the LED driver's auxiliary rail.
Recommended
Recommended Products Summary
Engineering reference data for ADC081S021CISD — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADC081S021CISD/NOPB | ADC101S021CISD | ADC121S021CISD | ADC081S021CIMFD | ADC081S021CIMF/NOPB |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 6-WSON (2.2x2.5) | 6-WSON (2.2x2.5) - same | 6-WSON (2.2x2.5) - same | 6-WSON (2.2x2.5) - same | 6-WSON (2.2x2.5) - same | 6-WSON (2.2x2.5) - same |
| Resolution | 8 bit | 8 bit | 10 bit | 12 bit | 8 bit | 8 bit |
| Sample Rate Range | 50-200 ksps | 50-200 ksps | 50-200 ksps | 50-200 ksps | 50-200 ksps | 50-200 ksps |
| Architecture | SAR | SAR | SAR | SAR | SAR | SAR |
| Supply Voltage | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V | 2.7 V to 5.25 V |
| Channels | 1 | 1 | 1 | 1 | 1 | 1 |
| Temperature Grade | -40 °C to +85 °C (industrial) | -40 °C to +85 °C (industrial) | -40 °C to +85 °C (industrial) | -40 °C to +85 °C (industrial) | Automotive grade (extended) | Automotive grade (extended) |
| Lead-Free / RoHS | Yes | Yes | Yes | Yes | Yes | Yes |
Key Differentiators
- Fully pin-compatible across 8/10/12-bit resolutions (vs ADC101S021CISD / ADC121S021CISD)
- Supply-as-reference architecture eliminates external reference IC (vs External-reference SAR ADCs (e.g., ADS7813UB/1K))
- Sub-1 µA shutdown current for battery-friendly duty cycling (vs Continuous-conversion 8-bit ADCs without shutdown pin)
- Compact 6-WSON (2.2x2.5 mm) footprint (vs MSOP-8 / SOT-23 8-bit ADCs)
Design Notes
Bypass VA with a 0.1 µF low-ESR ceramic capacitor placed within 2 mm of the VA pin. Because the ADC081S021CISD uses VA as its reference, any noise or ripple on the supply rail couples directly into the conversion result. For systems where VA is shared with digital logic, add a ferrite bead or 10 Ω resistor plus a second 0.1 µF cap to form a π-filter, isolating the ADC's reference from switching noise. A dedicated low-noise LDO for VA is recommended when the host rail is a switching converter output.
The 6-WSON package has an exposed thermal pad (EP) on the underside that must be soldered to a copper pad of at least the same footprint on the PCB. The EP is electrically tied to GND internally per the TI datasheet, providing both thermal dissipation and a low-impedance ground return. Use at least 4 thermal vias in the EP land pattern to push heat into inner ground planes and to reduce ground bounce. Do not route analog input traces under the EP to avoid coupling.
Keep analog input traces (VIN+, VIN-) short and symmetric, and route them away from the SPI clock (SCLK) and data (DOUT) lines to avoid digital-to-analog coupling. Place a small RC filter (typically 100 Ω + 1 nF) on each input if the source impedance is below 100 Ω or if the input bandwidth exceeds the Nyquist requirement. Add a 10 kΩ/10 kΩ resistor divider to bias single-ended inputs at mid-supply when measuring unipolar signals relative to ground, since the input range is true-differential around VA/2.
Do not leave the analog inputs floating - the ADC081S021CISD's true-differential input stage draws input bias current, and a floating input can cause the input common-mode to drift outside the valid range, producing saturated codes. Tie unused VIN- to VA/2 through a 10 kΩ resistor, or to GND if the application uses single-ended drive. Also note that the /CS pin must be driven low for the duration of a conversion; leaving it floating causes intermittent SCLK/DOUT activity and corrupted results.
Compliance Information
RoHS compliant per TI product page; lead-free terminal finish (matte tin). Not AEC-Q100 qualified for the CISD variant - choose MFD/MFD-NOPB for automotive. REACH compliance per TI product-level declaration.
